Why so much pain?

I'm 6months and 1 week pregnant... the past three days I've noticed the baby is extremely low(he's always been in my lower stomach) but now he seems way lower... I'm having a lot of pain and pressure by my pelvic bone and lower is this normal? I didn't have this with my first child and just nervous since I do a lot of physical work... I have an appointment t next Wednesday but wanted to know if this is normal ... sometimes the pain goes all the way down